Feb 27 (Reuters Health) - Physicians are failing to prevent blood clot formation in nursing home and hospital patients, leading to 60,000 to 100,000 preventable deaths each year, public health officials said Wednesday.

The deaths are mostly due to pulmonary embolism (PE), when a blood clot breaks off from the leg vein and lodges in the lung, cutting off the oxygen supply. As many as two million people--mostly those in hospitals, nursing homes or sick and immobile at home--develop leg clots, called deep- vein thrombosis (DVT), each year.

Two-thirds of DVT patients end up with chronic leg swelling, and as many as 600,000 develop the often-fatal lung clots, said Dr. Samuel Goldhaber, a professor at Harvard Medical School and an expert on the conditions.

"Despite these startling statistics, DVT is not capturing the level of public attention that it deserves," said Georges Benjamin, executive director of the American Public Health Association (APHA). "It continues to be an under-estimated, under-diagnosed and under-treated public health threat."

Despite recent reports about DVTs from long plane rides, there has not been any spike in DVT and PE. But public health specialists and many physician groups have become increasingly alarmed that despite ample evidence on what causes the clots and how to prevent them with blood thinners, there has been very little concerted action to stop them.

The APHA and the Centers for Disease Control and Prevention (CDC) are calling for a huge campaign to boost physician interest and to make Americans as acutely aware of their DVT and PE risk factors as they are for heart attacks and stroke.

In a survey released Wednesday, 74% of the 1,003 men and women queried had not heard of DVT or PE, and 57% could not cite any common risk factors.

Having surgery--and being inactive afterwards- -is the single biggest risk for developing a clot. Doctors and nurses are doing a much better job of preventing clots in surgical patients, said Goldhaber.

But many people with other risk factors are put into a hospital, nursing home or rehabilitation facility, and are not getting proper preventive treatment, he said. In a study of more than 5,000 patients with confirmed DVT, 71% had not received low molecular weight heparin, a blood-thinning medication that stops clot formation.

Risk factors include being overweight or a smoker; taking birth control pills or hormone replacement therapy; having cancer, paralysis, high blood pressure, heart failure or respiratory failure; and having a family history of DVT or PE. Some people also have inherited clotting disorders that put them at risk.

"Almost every patient admitted to a hospital today has risk factors," said Victor Tapson, a professor of pulmonary and critical care medicine at Duke University Medical Center.

Tapson said there are already good guidelines on clot prevention but that physicians don't follow them partly because they underestimate DVT and PE risk, or worry that the patients might have too much bleeding from the heparin.